A typical locking device for a tray in a supporting structure includes more than one locking device, for example a first locking device between the tray and the supporting structure, and a second locking device between the tray and the supporting structure. In the typical locking device, the first and second locking devices are not interconnected; the locking devices can be locked and unlocked separately. This arrangement can be troublesome for removal and/or installation if an operator does not lock or unlock both devices. For example, if the operator only locks the first locking device, the tray may not be as secure as when the second locking device is also locked, resulting in damage to the tray and components that may be mounted to the tray. Alternatively, if the operator only unlocks the first locking device and attempts to remove the tray, the tray may be damaged as the second locking device remains locked to the supporting structure. What is needed then is an interlocking device for a tray in a supporting structure that easily and completely disengages the tray when withdrawn by the operator, yet is secured by the interlocking device when the tray is inserted by the operator into the supporting structure.